In medical testing, the detection of photoluminescence or absorbance may be used as a mechanism to determine a characteristic of a sample of a biological fluid (otherwise referred to as “specimens” or “samples”). For example, in some automated testing systems (e.g., clinical analyzers) reaction vessels, such as cuvettes, flow through vessels, sample cups, vials, and the like, may receive samples (e.g., plasma) possibly containing one or more reagents (referred to herein as a “test sample”). The test sample in the test vessel may be provided in an illumination assembly. A light source may be projected through the test sample, and the light emanating from the test sample is detected by a photodetector. However, such systems may require the use of a reference detector to enable obtaining a reference value. Moreover, such systems may suffer from instability during use due to temperature variations of the light source.
Accordingly, methods, systems and apparatus that may improve accuracy and simplicity of illumination systems in clinical testing are desired.